Building Envelope Systems
Types of Cladding Covered
- Wood and metal
- Fiber cement
- Stucco and EIFS
Siding Assemblies
Wood Board Siding
- Attachment and overlap force water down the face of the wall and allow expansion/contraction of boards
- Blind nailing is when you nail behind one of the boards and the other board covers it when it overlaps
Beveled Wood Siding
- Siding that overlaps each other where the bottom is a little thicker than the top
Shiplap Wood Siding
- The wood is connected together and creates a dam so that water cannot get behind the wall
V-Groove Wood Siding
Board and Batten Siding
- It is usually done with 1 by which is actually ¾ in.
Fastening Cedar
- Most of the time they are fastened with coil nails
Open Joint Siding Systems
Rain screen
- Has a space in between the sheathing to allow water to flow through and have a way out instead of it getting trapped
Base Flashing
- A metal piece that helps with when moisture comes down the wall it is forcing water out and away
Fiber Cement Siding
- Made of cement reinforced with cellulose fibers
- May be large format or boards
- May be smooth or have integrated wood texture
- Prone to chipping on edge during installation
- Slower installation than wood- special nails and carbide or diamond blades must be used
- Nonflammable and heavier than wood or vinyl siding
- Highly resistant to moisture-will not shrink/expand or rot
- May be prefinished or painted in field-strong adhesive properties for paint coatings reduces need to re-paint as frequently as wood
Best Practices
- Exposure = how much siding material is exposed after lap
- Layout – care should be given to thoughtful layout that avoids small pieces around openings, corners, etc.
- Special conditions – corners may be mitered or trim placed to properly terminate boards
- Fastening – where possible, hidden fasteners are preferred
- Base flashing – z-shaped flashing should be used at base of assembly to force water away from the foundation
- Head flashing – metal flashing should also be placed above openings where the bottom of siding terminates
Stucco
- Stucco claddings and finishes vary, but can be organized into three main types:
- Traditional three-coat stucco
- Synthetic two-coat
- Exterior insulation and finish systems (EIFS)
Traditional 3-Coat System
- Traditional stucco consists of:
- Lath (usually metal)
- A scratch coat
- A brown coat
- And a finish coat
Synthetic Cement Board Stucco
- Cement board provides good impact resistance over traditional stucco and EIFS
- Less cracking than traditional stucco
- Requires placement of control joints at similar locations as masonry installations
EIFS
- Similar installation and layering as other synthetic stucco but uses rigid insulation in lieu of cement board
- Lighter, cheaper and faster to install than other systems
- Softer and less impact resistant than other stucco systems
- Early systems in 90s had significant moisture issues due to lack of drainage for water that penetrates system
Glass/Glazing + Windows
The Material Glass
- Common glass used is float glass – hot molten state glass that floats and solidifies on a bed of molten tin
- Float glass is made from
– Sand
– Soda ash
– Lime
– Alumina
– Potassium oxide
- Thickness range from approximately 3/32 inch (single strength) to 1/8 inch (double strength up to 1 inch
Glass Types by Heat Treatment and Strength
- Heat treatments impact glass strength and uses
- Annealed glass – regular float glass which is cooled slowly to reduce in built stress
- Tempered glass – produced by cutting annealed glass to required size, reheating and then cooling rapidly; higher strength and breaks into small shards
- Heat strengthened glass – between annealed and tempered with breakage behavior like annealed
- Laminated glass – sandwich of multiple layers of glass with PVB (polyvinyl butyral) interlayer; suitable for security applications as glass stays in place when broken
- Fire-rated glass
- Patterned glass – hot glass can be rolled into sheets with many different surfaces textures and patterns to obscure vision for privacy
- Fritted glass – pigmented glass particles called frits are used to imprint glass
- Glass is dried and fired in tempering furnace to make it permanent
- Spandrel glass – used to cover bands of floor/wall structure around the floor lines
- Usually tempered or heat strengthened with solid color behind them
Glass and Thermal Considerations
- Insulated Glass Unit (IGU)
- Made of multiple glass panels with sealed air space reducing conductance, single glazing is single glass, double glazing is two sheets and triple glazing is three sheets of glass
- Space filled by air or inert gas (argon) in a sealed cavity
- Low Emissivity coated glass (low-e)
- Formed with transparent metallic coating to improve thermal performance
- Located on surface 2 and sometimes on surface 3
- Improves thermal performance
- Visible Light Transmittance VT: Ratio of visible light passing to the amount striking the glass
- Solar Heat Gain Coefficient SHGC: Ratio of heat admitted to the amount striking the glass (lower is better)
- R-Value: Ability to resist heat flow (higher is better)
- U-Factor: Rate of heat transfer (inverse of R-Value)
Glazing Small Lights
- Not subject to excessive wind force or stresses due to thermal expansion
Types of Windows
- Fixed Windows
- Least expensive and least likely to leak air or water
- Hung Windows
- Maybe single hung or double hung depending on one or two moving sashes
- Sashes were hung by counterweights in the past but now use springs
- Sliding Windows
- Essentially like a single hung window on the side
- Inherently stable operable windows because of tracks
- Casement Windows
- Outswing units that are hinged on either side
- Generally narrow but can be joined to one another or with fixed windows
- Awning Window
- Outswing windows that hinge at top of frame
- Can be broad but not usually tall
- Can protect an open window from water during rainstorms
- Hopper Windows
- Swing in (to interior) from bottom hinge location
- Tilt/Turn Windows
Windows in Roofs
- Skylights
- Roof Windows
Glass Doors
- Large glass doors may slide on tracks or swing open on hinges
- French doors
- Open fully and are more welcoming
- Not easy to regulate air into the room because it can’t be kept partially open
- Prone to more air leakage
- Sliding doors
- Can be partially opened
- Can only open half its area
- Terrace doors
- Half leaf can swing open
Frame Types
- Wood
- Aluminum
- Aluminum-clad, wood-framed
- Plastic (vinyl, PVC)
- Steel
- Fiberglass/Composite
Wood Window Frames
- Traditional material for housing
- Good thermal insulator
- Low coefficient of thermal expansion
- Consistently strong
- Moisture related shrinkage a problem
- Requires repainting often and is subject to decay
- Wood frame windows can be clad with aluminum or vinyl
Aluminum Frames
- Strong, easy to form and join
- Less vulnerable to moisture damage
- Attractive profiles and colors – may be painted or anodized
- Durable factory finishes
- Require thermal breaks to reduce heat flow
- Mostly common in large buildings
Thermal Breaks
- They are internal components of insulating material that thermally isolate the aluminum on the interior side from the exterior side
- Inserting rubber, plastic gaskets or plastic strips into aluminum cavity
Plastic/Vinyl Frames
- Generally lowest cost option
- Do not need painting
- Provide good thermal resistance
- Not as stiff or strong as other materials
- Have high coefficient of thermal expansion
- PVC is the most common plastic used – associated negative environmental drawbacks
Steel Frames
- Used historically in warehouse buildings and some residential but not as common as now
- Main advantage is strength which permits sashes to be slender than other materials
- Corrosion is a problem so frames need to be coated or painted
- More thermally conductive than wood and plastic but less than aluminum
Aluminum Frame Glazing Systems
- Entrances
- These are systems of aluminum framed doors, hardware, aluminum framing and glass typically used in commercial buildings
- Storefronts
- These are based on simplified, lighter framing elements that are less expensive and quicker to assemble than curtain wall
- They are lighter and mostly used on single story
- Curtain Wall
- They are higher performance and can be used on any number of stories
Glazing Large Lights
- Large lights, those are over 6 ft, require more care in glazing due to stresses
- Design objectives are
- Support weight of glass without abnormal stress patterns
- Support glass against wing pressure and suction
- Allow for expansion and contraction of glass and frame without damage
- Avoid contact of glass with any hard material such as frame
- Setting blocks are synthetic rubber and support weight of glass
- Bite or depth of grip on the edge of glass of certain amount is required to resist win load
- Lockstrip gasket is a dry glazing method
- It is a faster, easier and less dependent on workmanship then wet glazing method
- Wet glazing requires better workmanship and is more effective
Aluminum Extrusions
- Very intricate aluminum sections can be extruded for variety of purposes including curtain wall components, door frames, window frames, entrances, storefronts, etc
Connection of Extruded Shapes
- Screw ports are extruded cylindrical features that allow a screw to be driven in parallel to the long axis of the extrusion
- Self-taping screws are driven through screw ports to fasten an extruded aluminum shear block
- Sanp-on and snap together features are commonly used in extruded aluminum framed components
Thermal Breaks
- This aluminum glazing extrusion relies on an extruded rubber gasket to act as a conductive separation between the pressure cap and the main body of the extrusion
Aluminum Surface Finishes
- Anodizing is a process that produces an integral oxide coating on the aluminum – it can be done in different colors
- Powder coatings are manufactured with thermosetting powders applied electrostatically
- Baked enamel finish consists of spray applied acrylic or polyester polymers and have high glass
Outside Glazed Systems
- In an outside glazed system the glass must be installed or replaced by glaziers
- High work requires they stand on scaffolding or lifts
Inside Glazed Systems
- In an inside glazed system workers stand inside the building to install the glass
- It is more convenient and economical for tall buildings
Installing Residential Windows
- Rough Openings – Slightly larger than actual window unit dimensions to account for discrepancies in plumb/level (usually ¼” larger in all directions)
- Attachment – Most residential units come with an integrated nail fin so the unit can be nailed or screwed to framing
- When measuring a window (e.g. 36×60 in. the first number is always the width)
Waterproofing Components
- Sill Pan
- Nail Fin and Integration into AWB system
- Head Flashing
- Caulking (You would only need to caulk the top and sides because water needs a place to escape through the bottom)
IRC Code Considerations
- Basements, habitable attics and every sleeping room must have at least one egress window
- Egress windows must have a minimum net clear opening of 5.7 SF (exception: grade floor windows must be 5.0 SF)
- Sill height may not exceed 44” above finished floor
- Where operable windows are placed above grade more than 6’, sill height must be minimum 24” from finished floor
Tempered Glass in Openings (Generally, some exceptions applied)
- IRC and IBC require safety glass at “hazardous locations”. Some rules:
- All glass doors regardless of size or operability
- All glass within 24” swing of a door if bottom edge of glass is less than 60” above floor
- Glass in bathrooms and wet areas less than 60” above floor
- Windows that meet all of the following:
-Larger than 9 SF
-Bottom edge is less than 18” above floor
-Top edge is more than 36” above floor
-Walking surface is within 36” (horizontally)
Ordering Windows
- Windows units used to be site built and glazed by highly skilled carpenters
- Now, nearly all window units are produced in factories to achieve high levels of productivity and precision
- Careful consideration must be given to placing purchase order for window units
- We must:
- Confirm sizes and colors
- Confirm operability and code compliance
- Account for lead times
Insulation
Inspections
- Foundation
- Ground EMP
- Slab
- Partial Frame (Sheathing)
- Rough-In MEP
- Final Frame
- Insulation
Types of Insulation
- Blanket: Batts and Rolls
- Loose-Fill and Blown-In
- Spray Foam
- Rigid Foam
- Structurally Integrated Insulation Systems
Blanket Insulation
- Consists of flexible fibers – can be fiberglass, mineral wool, natural fibers (cotton, sheep wool), or recycled fiber (denim)
- Batts and rolls are available for standard wall stud spacing – 16” and 24” on center
- May be continuous roll or precut
- Available with or without facing (faced or unfaced), usually kraft paper – acts as vapor barrier and facilitates stapling in place
- Unfaced batts are friction fit without attachment
Installing Batts
- Batt insulation is relatively simple to install
- Generally is lowest cost option
- Difficult to address air infiltration with batts alone
- Must not compress in cavity
- Must take proper approach around wiring and piping
Installing Batts
- Batt installation is relatively simple to install
- Generally is lowest cost option
- Difficult to address air infiltration with batts alone
Joist Hanger
- Metal bracket that holds the joists to the LVL
Loose-Fill and Blown-In Insulation
- Consists if small particles, usually fiberglass or cellulose, that conform to space in which they are blown; have fire retardant components (borate or ammonium sulfate)
- Most cellulose is manufactured using recycled material (recycled news print)
- Fiberglass contains 40% to 60% recycled glass
- Installed with blower machine into walls nets (net and blow) or loose-filled onto horizontal surfaces, like attic floors
- May be “wet sprayed” without nets
Wet or Damp Sprayed Cellulose
- Integral adhesive is activated with water when blown into place
- Similar to spray foam, cavity is over-sprayed and cut back after dry
- Debate exists about the moisture content in these systems, especially if vapor barrier is used
- Typically is dry enough for drywall in 3 days +/-
Measuring R-Value
- Federal Trade Commission issued the “Trade Regulation Rule Concerning the Labeling and Advertising of Home Insulation”
- R-Value Rule prohibits unfair or deceptive acts or practices on reporting R-Values associated with various products
- R-Value ratings vary among different types and forms of insulations and among products of the same type and form
- Manufacturers and installers must disclose relative information about R-Values (coverage, thickness)
Loose-Fill and R-Value
- As the installed thickness of loose-fill insulation increases, its settled density also increases due to compression of the insulation under its own weight
- So… R-Value of loose-fill insulation does not change proportionately with thickness
Cellulose vs Fiberglass
- Fiberglass is subject to “fluffing” during installation – using more air than specified to inflate the thickness of the material, resulting in lower density and lower R-Value
- Specifically prohibited by the R-Value Rule
Spray Foam
- Spray polyurethane foam (SPF) shot in place into open wall/roof cavities
- Best product at sealing air leakage/penetrations
- Open-cell foam is vapor permeable (breathes) and is 0.5 lb/cubic foot
- R-value = 3.5 per inch
- Use water or CO2 as blowing agent
- It has a yellow color
- Closed-cell foam is a vapor retarder and is 2 lb/cubic foot
- R-value = 6.5 per inch
- Use hydrofluorocarbons (HFCs) as blowing agent
- It has a blueish color
Spray Foam Considerations
- Cost of spray foam has decreased over recent year to compete with blown-in
- Performs like R-24 in 3.5” wall because of closing air infiltration
- Spray foam can shrink and pull away from wall framing (more common in closed cell than open cell installations)
- Attention should be given to ventilation and humidity levels in foam envelopes
- Where spray foam is left exposed (attics, crawl spaces, etc.), a built-in ignition barrier is required to ensure the material does not inflame
- In areas dedicated to storage, exposed insulation requires a thermal barrier coating
Effective R-Value
- Nominal Insulation accounts for insulation layer only
- Effective Insulation accounts for insulation, thermal bridging from framing, interior finish, sheathing and cladding